Hydraulic device



* July 22, 1958 P. KJWENNBERG 2,844,104

HYDRAULIC DEVICE Filed June 14. 1954 v 3 Sheets-Shee t 1 INVENTOR.

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ATTOI/l/fi y 1958 P. K. WENNBERG 2,844,104

HYDRAULIC DEVICE 3 Sheets-Sheet 2 Filed June 14. 1954 m\ Emu-Em:

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TOFA/E'F y 22, P. K. WENNBERG 2,844,104

HYDRAULIC DEVICE Filed June 14, 1954 I a Sheets-Sheet s mm-llnmnznm INVENTOR. P5015? K W F/VA/BRG BY wxz;

United States Patent HYDRAULIC DEVICE Application June 14, 1954, Serial No. 436,369

11 Claims. c1. 103 -162 This invention relates to fluid energy translating devices such as hydraulic pumps, transmissions, motors and the like, and more particularly to that type of hydraulic unit that includes. a rotating cylinder barrel provided with a plurality of cylinders and pistons reciprocable therein and a stationary valve plate cooperating With the cylinders to properly direct and control the flow of operating fluid.

In fluid energy translating devices of this type, leakage of operating fluid under pressure intermediate the rotating cylinder barrel and the stationary'valve plate results in reductions of operatingefliciencies. This reduction in efiiciency in general becomes more pronounced as the operating pressures increase. The loss in. efficiency re sulting from leakage of operating fluid under pressure and its importance in devices of vthis nature wasearly recognized, and many improvements in the form of mechanical seals, packings and sealing structures based uponmechanical prevention of leakage are well known in the art. However mechanical sealing arrangements madeinl accordance with more or less conventional construction, while providing satisfactory and adequate performance at low operational pressures have proved to be unsatisfae tory and inadequate for high pressure operations.

Fluid energy translating devices of theparticular type with which we are here concerned conventionally employ restricted ports in the ends of the cylinders disposed adja cent the valve plate. These port restrictions, While serv-. ing an important operating function, lead to serious machining gdifliculties in the manufacture of the unit, such as precluding the'utilization of straight-throughboring and lapping operations, and necessarily, add to the.expense of the finished unit. The port restrictions also result, in operation, in relatively high fluid velocities and undesirable cavitation effects resulting therefrom aswell as in the possibility of undesirable bending moments being applied to the drive shaft for the unit. The improved sealing structure described herein eliminates the conventional port restrictions, and as such permits'economies of manufacture such as, for example, those attainableby straightthrough boring and lapping operations on the cylinder barrel as well as for providing for lowered velocity for the operating fluid and reduced cavitation effects.

The invention described herein may be .consideredas an improvement over the early United States Patent No. 737,876 to Smallbone and incorporates an improved sealing structure mounted in the rotating member utilizing the operating pressures to maintain the seal intermediate stationary and moving members. v s

This invention may be briefly described as an improved sealing structure adapted to be incorporated in the rotat valve plate 1 0. as by the bolts 22 are the right-hand and the advantages flowing from the utilization of the invention herein described is that it permits straight-through boring on the same centers and with the same diameter of cylinder barrels through the elimination of the usual port restriction commonly found in devices of this general nature. The elimination of conventional port restriction also results in minimization of bending moments on the drive shaft as well as lower fluid velocities to and from the cylinder barrels and an accompanying minimization of cavitation effects. The invention also permits the manufacture of fluid energy translation devices capable of operating at higher pressures than heretofore utilized as well as permitting operations at higher efliciencies at pressures that are conventionally employed. Moreover the structure of this invention is relatively simple and inexpensive, and is such as to permit decided economies in manufacturing and maintenance costs as compared to similar costs encountered in present day structures.

An object of the invention is the provision of an improved sealing structure for fluid energy translationg devices.

Another object of this invention is the provision of an improved sealing arrangement for high pressure fluid energy translating devices wherein the operating pressure is utilized to maintain the seal intermediate the stationary and rotating elements thereof.

A still further object of this invention is the provision of an improved construction for fluid energy translation devices which permits straight-through boring and lapping operations on the cylinders through elimination of conventional port restriction therein.

Other objects and advantages of the invention will be pointed out in the following disclosure and claims and illustrated in the accompanying drawings which disclose by way of example, the principle of the invention and the presently preferred embodiment thereof as incorporated in a fluid energy translating device such as, for example, a hydraulic pump.

Referring to the drawings:

Fig. 1 is a plan view of the exterior of a hydraulic pump constructed in accordance with the principles of this invention;

Fig. 2 is a side elevational view of the pump illustrated in Fig. 1;

Fig. 3 is an end elevational view of the pump illustrated in Fig. l;

Fig. 4 is a sectional view on the line 44 of Fig. 3;

Fig. 5 is a sectional view on the line 55 of Fig. 4;

Fig. 6 is a sectional view on the line 6 6 of Fig. 5;

Fig. 7 is a front elevational view of the sealing plate;

Fig. 8 is a sectional view on the line 8--8 of Fig. 7;

Fig. 9 is an enlarged front elevational view of the sealing sleeve;

Fig. 10 is a sectional view on the line 1010 of Fig. 9;

Fig. 11 is a front elevational view of the cylinder barrel; and

Fig. 12 is a sectional view on the line 1212 of Fig. 11.

The subject matter of the present invention is illustrated as incorporated in a double action hydraulic pump for the purposes of example, it being understood that the same could be similarly incorporated in other types of fluid energy translating devices, such as hydraulic transmissions or motors. The illustrated pump generally is of more or less conventional construction and, as illustrated particularly in Figs. 1 through 4, it includes a centrally disposed stationary valve plate 10 provided with suitable operating fluid entry and delivery ports therein such as 12 and 14. The stationary valve plate 10 is also provided with a base or operating pedestal 16 for mounting and installation purposes. Secured to either side of the left-hand housing members 18 and 20, respectively. The left-hand housing member 20 may also be designated as the control housing and is closed by an end cover 24. The right-hand housing member 18 is closed by an end cover 26 having a suitable aperture therein containing an end bearing and seal retaining member 30 to permit passage of the drive shaft 28 therethrough. Suitable packing rings 29 are disposed intermediate the valve plate 10 and the right-hand and left-hand housing members 18 and 20, respectively, and also intermediate the right-hand housing member 18 and the end cover 26.

Referring now particularly to Fig. 4, the drive shaft 28 for the pump is preferably journaled in an anti-friction drive shaft bearing 32, the outer race of which is mounted in a suitable recess in the end cover 26 and is positioned therein by the abutting end bearing and seal retaining member 30 which is secured to the end cover 26 p as by the illustrated bolts 33. As illustrated, the drive shaft 28 is provided with a splined surface at two distinct locations thereon, as at 34, 34, with the portion thereof disposed intermediate the splined portions 34 being rotatably contained within a suitablysized and centrally disposed bore 36 in the stationary valve plate 10.

Disposed on either side of the stationary valve plate 10 and rotatably mounted on anti-friction cylinder bearings 38 within the left-hand and right-hand housing members 18 and 20, respectively and on the drive shaft 28 are the right-hand and left-hand cylinder barrels 48 and 42. Each of the cylinder barrels 4t) and 42 is provided with a central bore 44 (see Figs. 11 and 12) having a splined surface 46 over the portion of its length adapted to engage the correspondingly splined portions 34 of the drive shaft 28 and to be thereby rotatably driven within their respective housing members in accordance with rotation of said drive shaft 28. Suitable end retaining rings 41 are provided to aid in the positioning of the cylinder barrels 40 and 42 on the drive shaft 28.

The cylinder barrels 40 and 42 each contain a plurality of cylinders 48. Reciprocably disposed within each of the cylinders 48 is a piston 50. Each of the pistons 50 is suitably connected at the exposed end thereof to a piston shoe 49 positioned against a rotatable thrust plate 52 by the piston shoe retainer ring 51. The thrust plate 52 supports the rotating race 53 of the swash plate bearing 56, the stationary race of which is mounted in a non-rotatable control yoke 54. As is conventional with this construction, the angular position of one of the con-' trol yokes 54, for example that disposed within the control housing 20, is rendered adjustable so as to permit any desired angle of tilt thereof and the other control yoke 54 is maintained in fixed angular position within the end cover 26. As the angular disposition of the control yokes 54 determines the length of stroke of the pistons 50, the operating characteristics of the illustrated pump are controlled in accordance with the angular disposition of the displaceable control yoke 54.

Referring now also to Figs. and 6, the valve plate is suitably shaped so as to connect the fluid entry port 12 to the arcuate ports 58 disposed on the surface of the valve plate 10 adjacent each of the abutting cylinder barrels and in register with the cylinders 48 therein. In a similar manner the valve plate 10 is suitably shaped so as to connect the fluid delivery port 14 to the arcuate ports 60 disposed on the surface of the stationary valve plate 10 adjacent each of the abutting cylinder barrels and in register with the cylinders 48 therein.

In operation of the device, rotation of the drive shaft 28 results in rotation of the cylinder barrels 40 and 42 within the right and left-hand hoosing members 18 and 20, respectively. The rotation of the cylinder barrels 40 and 42 with respect to the stationary and angularly disposed control yokes 54 results in reciprocation of the pistons 50 contained within the cylinders 48. The control yokes 54 are positioned so that the pistons 50 contained within the cylinders 48 that are disposed in fluid contact with the arcuate ports 58 in the valve plate 10 are being withdrawn from said cylinders. The retraction of these pistons results in operating fluid being drawn into the space in the cylinders 48 vacated by said pistons 50 through the fluid entry port 12 and the arcuate ports 58. As the cylinder barrels 40 and 42 rotate, the cylinders 48 filled with operating fluid in the manner set forth above are rotatably displaced into sequential engagement with the arcuate exit ports in the valve plate 10. As the respective fluid-filled cylinders 48 come into engagement with the arcuate ports '60, the pistons 50 disposed therein are forced. forwardly under the action of the angularly disposed control yoke 54 and thereby displace the fluid from the cylinders, through said arcuate ports 60 and through the fluid delivery port 14. Thus it will be seen that rotation of the drive shaft 28 results in rotation of the cylinder barrels 40 and 42 and in reciprocation of the pistons 50 in such a manner as to draw operating fluid into the pump through intake or entrance port 12 and to deliver fluid through the delivery port 14.

In devices of this type adapted to operate under high pressures, the operating fluid being expelled from the cylinders 48 is subjected to the operating pressure due to the action of the advancing pistons 50. As the cylinder barrels are in continual rotation during operation, the

operating pressures: on the fluid will attempt to force the fluid or a portion thereof through the joint intermediate the rotating cylinder barrel, for example 42, and the stationary valve plate 10. This leakage of operating fluid under pressure, if excessive, results in marked reduction of operating efiiciencies. The amount of leakage of course is in part determined by the amount of pressure exerted so as to press the rotating cylinder barrel against the valve plate 10, but it will be readily recognized that such pressure increases the friction intermediate the stationary and moving surfaces and results, if undue pressure is applied, in increased power losses and in increased wear on the engaged surfaces. The operating pressures also, in conventional construction with'restricted cylinder ports, result in the application of undesirable bending moments to the drive shaft as well as in cavitation effects in the port system resulting from high fluid velocities.

Referring now to Figs. 4, l1 and 12, the individual cylinders 48 within the cylinder barrels, as for example cylinder barrel 42, are provided with an enlarged bore of uniform internal diameter at the end thereof adapted to be disposed adjacent the stationary valve plate 10. The enlarged bore 70, together with the cylinder 48, provides an internal shoulder 72 within each of the cylinders 48.

Adapted to be slidably disposed Within each of said enlarged bores 70 is a ported displaceable means such as a closely fitting sealing sleeve 74 as illustrated in enlarged scale in Figs. 9 and 10. The sealing sleeves 74 are provided with a central bore 76 sized in diameter to equal the radial dimension of the aperture of the arcuate ports 58rand 60 0f valve plate 10. At the end 78 of the sealing sleeves 74, which end is adapted to be disposed facing the shoulder 72 within the cylinders 48, there is provided a beveled surface 80, one extremity of which provides a bore 82 equalling or closely approximating that of cylinders 48' and the other extremity of which defines the bore 76. The outer surface :of each of the sealing sleeves 74 is provided with a pair of spaced abutments 84 and 86. The vertically disposed surface 88 of abutment 84 provides an operating surface against which a biasing spring 90 (see Fig. 4) may operate. The recess 92 formed intermediate the abutments 84 and 86 serves to provide a recess for the mountingof a packing ring 94 such as a conventionl O ring see (Fig. 4)". The abutment 86 also serves to provide an external shoulder 96 to determine the length of the seal plate mounting surface 104 and thus serves to position and locate the 'seal plate 98 when the seal plate (see Figs. 7 and 8) is mounted on the surface 104 of the sealing sleeves 74. i

The seal plate 98 is provided with a central bore 100 sized to freely contain the drive shaft 28 and is additiona1- ly provided with a plurality of spaced apertures 102 positioned to register with the cylinders 48 in the cylinder barrels 40 and 42 and sized to contain the extended portions 104 of the sealing sleeves 74 as by a shrink fit. The seal plate 98 is ofa thickness so that when it-is positioned in place on the sealing sleeves 74 with one side thereof disposed closely adjacent the shoulders 96, the other side of the seal plate '98 is disposed flush with the ends of the sealing sleeves 74 adapted to bepositioned adjacent the valve plate 10.

Thesurfaces of thevalve plate adapted to face the rotating cylinder barrels 40 and 42 are provided with raised abutrnents 110 in the portions thereof immediately surrounding the arcuate ports 58 and 60. Theradially' measured'thickness of each side of this raised abutment 110 is preferably less than the radially measured wall thickness of the smaller diameter ends of the sealing sleeves 74 (which as illustrated in Fig. 4 are adapted to engage said abutment) and should be made as small as practicable in the radial dimension. As explained in greater detail at a later point in this specification, the area of the raised abutment must be small enough to give the desired sealing pressure.

Fig. 4 shows the component elements. above described in assembled relationship in theillustrated pump. As there illustrated, a sealing sleeve 74 is slidablyv disposed within the enlarged bores 70 of each of the cylinders 48 in the cylinder barrels 40 and 42, respectively. The surfaces of the sealing sleeves 74 and theenlarged bores 70 should be carefully machined so as to provide the tightest possible fit that permits sliding displacement of the sleeves 74 within the bores 70. Moreover the sealing sleeves 74 should be as rigid in nature as possible to prevent any de-' formation thereof under load and consequent binding within the bores 70. Disposed intermediate each of the shoulders 72 in the cylinders 48 and the adjacents surface 88 of the sealing sleeves 74 is a biasing spring 90 adapted to maintain the sealing sleeves 74 and the seal plate 98 in engagement with the raisedabutment 110 of the stationary valve plate 10 when the sealing sleeves 74 are not subjected to the operating pressures. Disposed within each of the-recesses 92 intermediate the abutments 84 and 86 on the outer surfaces of the sealing sleeves 74' is a packing ring 94 such as an O ring adapted to prevent leakage of operating fluid through the joint, intermediate the outer surface of the sealing sleeve -74'and the enlarged bore of the cylinders 48 under operating pressures.

In order to obtain an effective seal intermediate the stationary valve plate and the rotating cylinder barrel for high pressure operations it is highly desirable that the dimensions of the constitutent elements be proportioned so that the unit pressure tending to maintain the seal bear a predetermined relationship to the working pressure for the unit. For example, in operation of the devicede- I scribed above, the net force for a given operating or working pressure acting to break the seal intermediate the valve plate 10 and the rotating cylinder barrel on "the high pressure side of the unit is equal to the productof the working pressure and the elfective metal area on the seal plate and sleeves upon which this pressure acts. This effective metal area may be readily determined by sub tracting from the area of. one of the arcuate ports-60 in' the valve plate 10 the minimum cylinder port areain registry therewith at any time in .the rotative cycle.

In contradistinction therewith, the net force acting to This latter 6 to maintain the seal should of course be greater than the net 'force'tending to break the seal.

The difference between the net forces tending to break and to maintain the seal is then divided by the bearing area of the seal plate 98 and sleeves 74 on the abutment of the valve plate 10 to obtain the unit sealing pres sure. This unit sealing pressure should be at least 60% and preferably more of the working pressure for eflective results.

In accordance with the provisions of the patent statutes, I have herein described the principle of operation of this invention, together with the elements which I now consider to constitute a workable embodiment thereof, but I desire to have it understood that the structure disclosed is only illustrative and the invention can be carried out by other means. Also, while it is designed to use the various features and elements in the combinations and relations described, some of these may be altered and modified without interfering with the more general results outlined. 1

Having thus described my invention, I claim:

1. In a fluid energy translating device of the type having a valve plate with arcuate ports therein and an adjacent relatively rotatable cylinder barrel containing a plurality of spaced cylinders disposed in registry with the arcuate'ports in said valve plate, a sealing structure comprising a raised sealing surface surrounding the arcuate ports in said valve plate, an enlarged bore in the portion of the cylinders disposed adjacent to the valve plate, sleeve means slidably mounted in substantially fluid tight relationship in each of said enlarged bores and extending therefrom into engagement with said raised sealing surface, and a plate member mounted on the extended portions of said sleeve members and disposed adjacent the raised sealing surface in the valve plate.

2'. In a fluid energy translating device of thetype having a valve plate with arcuate ports therein and an adjacentrelatively rotatable'cylinder barrel containing a plurality of spaced cylinders disposed in registry with the arcuate ports in said valve plate, a sealing structure comprising a raised sealing surface surrounding the arcuate ports in said valve plate, sleeve means slidably mounted in substantially fluid tight relationship in each of said cylinders and extending therefrom into engagement with said raised sealing surface, and a plate member mounted on the extended portions of said sleeve members and disposed adjacent the raised sealing surface in the valve plate.

3. In a fluid energy translating device of the type having a valve plate with arcuate ports therein and an adjacent relatively rotatable cylinder barrel having a plurality of spaced cylinders disposed in registry with the arcuate ports in said valve plate, a sealing arrangement comprising a raised sealing surface surrounding the arcuate ports in said valve plate, ported displaceable means contained in substantially fluid tight relationship within each of the cylinders in said cylinder barrel adapted to be displaced adjacent said valve plate by the operating pressure of said device, and a plate member mounted on said ported displaceable means and displaceable therewith into sealing engagement with said raised sealing surface on said valve plate.

4. In a fluid energy translating device of the type having a valve plate with arcuate ports therein and an adjacent relatively rotatable cylinder barrel containing a plurality of spaced cylinders disposed in registry with the arcuate ports in said valve plate, a sealing structure comprising a raised abutment entirely surrounding the arcuate ports in said valve plate, an enlarged bore of uniform diameter in the portion of the cylinders in the rotatable cylinder barrel disposed adjacent to the valve plate, a sealing mounted on theextended portions of said sleevemembers and disposed adjacent said raised abutment on said valve plate, the dimensions of said raised abutment, arcuate ports, sealing sleeves, and seal plate being proportioned so that the sealing force operating on said seal force receiving surface to maintain the seal intermediate the valve plate and the cylinder barrel provides a sealing pressure of a magnitude of at least 60 percent of the Working pressure of the fluid energy translating device.

5. The sealing structure as set forth in claim 4 including means for maintaining said seal plate in engagement with said raised abutment when said sealing sleeves are not subjected to the working pressure of said device.

6. In a fluid energy translating device of the type having a valve plate with arcuate ports therein and an adjacent relatively rotatable cylinder barrel containing a plurality of spaced cylinders disposed in registry with the arcuate ports in said valve plate, a sealing structure comprising a raised abutment surrounding the arcuate ports in said valve plate, an enlarged bore of uniform diameter in the portion of the cylinders disposed adjacent to the valve plate, sleeve means slidably mounted in substantially fluid tight relationship in each of saidenlarged bores and extending therefrom into engagement with said raised abutment surrounding the arcuate ports in said valve plate and provided with a sealing force receiving surface, a plate member mounted on the extended portions of said sleeve means and disposed adjacent said raised abutment, the dimensions of said raised abutment, arcuate ports, sleeve means, and plate member being proportioned so that the pressure operating to maintain the seal bears a predetermined relationship to the Working pressure of the fluid energy translating device sufficient to prevent detrimental leakage of operating fluid intermediate said valve plate and the cylinder barrel.

7. In a fluid energy translating device of the type having a valve plate with arcuate ports therein and an adjacent relatively rotatable cylinder barrel containing a plurality of spaced cylinders disposed in registry with the arcuate ports in said valve plate, a sealing structure comprising a raised sealing surface surrounding the arcuate ports in said valve plate, an enlarged bore in the portion of the cylinders disposed adjacent to the valve plate, sleeve means slidably mounted in substantially fluid tight relationship in each of said enlarged bores and extending therefrom into engagement with said raised sealing surface, a plate member mounted on the extended portions of said sleeve means and disposed adjacent said raised sealing surface, the dimensions of said raised sealing surface, arcuate ports, sleeve means, and plate member being proportioned so that the pressure operating to maintain the seal bears a predetermined relationship to the working pressure of the fluid energy translating. device suflicient to prevent detrimental leakage of operating fluid intermediate the valve plate and the cylinder barrel.

8. In a fluid energy translating device of the type having a valve plate with arcuate ports therein and an adjacent relatively rotatable cylinder barrel containing a plurality of spaced cylinders disposed in registry with the arcuate ports in said valve plate, a sealing structure comprising a raised sealing surface surrounding the arcuate ports in said valve plate, an enlarged bore in the portion of the cylinders disposed adjacent to the valve plate, sleeve means slidably mounted in substantially fluid tight relationship in each of said enlarged bores and extending therefrom into engagement with said raised sealing surface, a plate member mounted on the extended portions of said sleeve means and disposed adjacent said raised sealing surface, the dimensions of said raised sealing surface, arcuate ports, sleeve means, and plate memher being proportioned so that the pressure operating to maintain the seal intermediate the valve plate and the cylinder barrel is at least 60 percent ofthe working pressure of the fluid energy translating device.

9. In a fluid energy translating device of the type having a valve plate witharcuate ports therein and an adjacent relatively rotatable cylinder barrel containing a plurality of spaced cylinders disposed in registry with the arcuate ports in said valve plate, a sealing structure comprising a raised sealing surface surrounding the arcuate portsinsaidvalve plate, a sleeve member Slide ably mounted in substantially fluid tight relationship in each of said cylinders and, extending therefrom into engagement with said-raised sealing surface and provided With a sealing force operating surface, a plate member mounted-0n the extended portions of said sleeve members and disposed adjacent said, raised sealing surface, the dimensions of said raised sealing surface, arcuate ports, sleeve members, and plate member being proporti'oned so that the sealing force operating on said seal force receiving surface to maintain the seal intermediate the valve plate andthe. cylinder barrel provides a sealing pressure of suflicient magnitude. inrelation to the working, pressure of the. fluid energy translating device to prevent detrimental leakage.

10. Ina fluid energy translating device of the type having a valve plate with arcuate ports therein and an adjacent relatively rotatable cylinder barrel containing a plurality, ofvspacedcylinders disposed in registry with the arcuate ports vin said valve plate, a sealing structure comprising araised abutment surrounding the arcuate ports. in said valve plate, a sleeve member slidably mounted in substantially fluid tight relationship in each of said cylinders and extending therefrom into engagement with said raised abutment surrounding the arcuate ports in said valve plate, a'plate member mounted on the extended portions of said sleeve members and disposed, adjacentsaid raised abutment, the dimensionsv of said raised abutment, arcuate ports, sleeve members, and platemember being proportioned so;-that the pressure operating to maintain the seal intermediate. the valve plate and the cylinder barrel is at least 60 percent of the working pressure of the fluid energytranslating device.

11. In a fluid energy translating device of the type having a valve plate with arcuate portstherein and an adjacent. relatively rotatable cylinder barrel containing a plurality of spaced cylinders disposed in:registry with the arcuate ports in said valve plate, a sealing structure comprising a raised abutment surroundingthe arcuate ports in said valve plate, a sleeve, member slidably mounted in substantially fluid tight relationship. in each of said cylinders and extending therefrom into engagementwith said raised abutment surrounding the arcuate ports in said valve plate, a plate member mounted on the extended portions of said sleeve members, and disposed adjacent said raised abutment on said valve plate,

the dimensions of said raised abutment, arcuate ports,.

sleeve members, and plate memberbeing proportioned so that the pressure operatingto maintain'the seal bears a predetermined relationship tothe working pressure of the fluid energy translating device, suflicient to prevent detrimental leakage of operating fluidintermediate said valve plate and the cylinder-barrel.

References Cited in the file of this patent UNITED STATES PATENTS 

